1. Field of the Invention
The invention relates in general to orthodontic apparatus for performing orthodontic treatment and in particular to elastomeric orthodontic bands and brackets for use with arch wires and elastic connectors.
2. Description of the Prior Art
In the science of orthodontics there has been developed two techniques and the associated apparatus for straightening teeth. The "edgewise" technique was developed first and employs orthodontic brackets having a horizontal slot for receiving a single rectangular arch wire. The arch wire is retained by brackets attached to adjacent teeth and is bent to achieve "tipping" (rotation of the tooth about the buccal-lingal axis toward or from adjacent teeth) or "torquing" (rotation of the tooth about the mesial-distal axis toward or from the palate). The rectangular arch wire is usually relatively large in diameter and is painful to the patient since large rotational forces are generated.
The "light-wire" technique was developed in an attempt to avoid the painfully large rotational forces of the "edgewise" technique. A thin round wire is utilized to reduce the rotational foces while achieving results which are as effective as those obtained with large rectangular or round wires. In addition there is less friction between the bracket and the wire so that the teeth can move much more easily.
Early prior art orthodontic devices were made from metal which was strong but not aesthetically pleasing. U.S. Pat. No. 3,504,438 issued to H. P. Wittman et al shows an orthodontic appliance comprising a band and a bracket with an exterior surface covering of a polymeric material such as Teflon which not only produces a pleasing aesthetic appearance but also has a low coefficient of friction to aid in the movement of the teeth. A further development is shown in the Northcutt U.S. Pat. No. 3,765,091 wherein an orthodontic onlay is an integral rigid plastic member which will not give to the forces applied by the arch wire. The plastic material may be clear or may be tooth color to provide a pleasing aesthetic appearance.